Chapter 3 Water Flashcards
What % of the Earth is covered in water?
75%
What % of the human body is water?
70-90%
What are the 4 emergent properties of water?
- Cohesive Behavior
- Ability to Moderate Temp.
- Expansion upon Freezing
- Universal Solvent
What makes water cohesive ?
H-Bonds
Cohesive
The attraction of molecules for other molecules of the same kind
Adhesion
the tendency of water molecules to attracted, or “stick”, to other substances
Surface Tension
how difficult it is to break the surface of a liquid
What is surface tension affected by?
Temp.
What is heat?
the energy associated w/movement of atoms &, molecules in matter
Temperature
measures the intensity of heat
What causes H-bonds to break?
Heat is being absorbed
What happens when H-bonds form?
Heat is released
Specific Heat
the amount of heat that must be absorbed or lost to change the temp of 1 g of a substance by 1 degree C.
Water: 1 C/g
Ethyl: 6 C/g
Acetone: .51 C/g
What does Specific Heat allow large bodies of water to do?
It allows large bodies of water to absorb & store large amounts of heat while changing the temp. slightly. Allowing ocean’s temps to fluctuate less than land.
Heat of Vaporation
The energy/heat required to change 1g of water from liquid to gas
Evaporative Cooling
When people sweat, water molecules are released from the body (the one w/ the highest energy leave) The molecules that are left behind have less energy & therefore cool down.
As sweat evaporates it absorbs heat to cool your body
What is less dense liquid water vs ice
Ice
Why is water less dense as a solid?
H-Bonding, the orientation of the bonds causes molecules to push farther apart which lowers density
What temp. is water densest?
4 degree C
What happens to the density of water lower than 4-degree C
The density decreases.
B/c of Water’s expansion it prevents deep bodies of water from doing what?
Freezing bottom up
As water freezes, what happens to the water below?
It gets insulated b/c of the release of heat
What factors the seasonal transition of water less abrupt?
H bonds breaking absorbing heat & H-bonds forming releasing heat.
Solution
liquid consisting of a uniform mixture of 2 or more substances
Solvent
dissolving agent
Solute
substance that dissolves
Hydrophilic
Affinity to H20
Polar
Ion
Sugar & Salt
Blood
Hydrophilic
Affinity to H20
Polar
Ion
Sugar & Salt
Blood
Hydrophobic
Repel H2O
Nonpolar
Oil & Lipids
Cell Membrane
What do water molecules dissociate into?
H+ and OH-
What do water molecules dissociate into?
H+ and OH-
H+ + H2O = H3O+
Hydronium ion
H20 - H+ =OH-
Hydroxide ion
Acid
Increase in H+ concentration
less than pH of 7
More H+ than OH-
Bases
Decrease of H+ in a solution
More OH- than H+
greater than 7
Buffer System
Consists of a weak acid & its conjugated weak base
Accept H+ ions when they are in excess & donate them when they are depleted
Dissociate to replenish H+
Reassociate when H+ is too high
Which property explains the ability of a water strider to walk on water?
Surface Tension
3 effects of heat of vaporization
Moderates Earth’s climate
Accounts for severity of steam burns
Releases heat and forms rain
Ice floats, why is this property so important ?
If ice sank , eventually all ponds would freeze over, kill life
Why is water such a fine solvent
Polarity & Hydrogen Bonds, molecules as large as proteins can dissolve in water as wall as bio fluid, sap & liquid in cells
Olive oil doesn’t dissolve in water, explain in terms of hydrogen bonding?
Oils are nonpolar molecules, hydrophobic molecules related to oils are a big part of cell membranes & are hydrophobic so the membrane doesn’t dissolve. So for oil to dissolve in water they would have to break some of water’s hydrogen bonds.
Oil is nonpolar because of this in order for oil to dissolve it would have to break water’s hydrogen bonds. Which water will not do so they are separate.
Calorie
the energy needed to raise the temp. of 1 g of water through 1 degree C.
How does water high specific heat contribute to moderation of temp. How is this an important property for life?
Water’s high specific heat makes it so that it takes a long to heat up & longer to cool down than the air & land. Which is important to the life that live in large bodies of water who needed a consistent temp. to live.
Evaporation
liquid water changes to gaseous water
